Since a fluorine containing elastomer, in particular, a perfluoro elastomer, comprising a tetrafluoroethylene (TFE) unit as a main, exhibits excellent chemical resistance, solvent resistance and heat resistance, it is widely used as a seal material and the like under severe environment such as an aerospace field, a semiconductor production device field and a chemical plant field.
Among those, in a semiconductor production step, CVD is used as a step of forming an insulation film and a metal wiring thin film, and elastomeric seal materials are used for sealing various linking portions and mobile portions in a CVD device. It is required for these seal materials that they have not only seal properties but also can endure severe plasma processing conditions at a high density (1012 to 1013/cm3) caused by miniaturization and jumboization of a substrate wafer and do not stain a semiconductor which is required to have a extreme precision process. A crosslinkable fluorine containing elastomer and a silicone elastomer are adopted as the elastomeric material for the seal material which can satisfy such a requirement. Further, an organic or an inorganic filler is usually compounded for attaining more sufficient mechanical strength than in case of crosslinkable an elastomer alone. Examples of fillers conventionally used or proposed are carbon black, silica (for example, see Japanese Patents No. 2783576 and No. 2858198), polytetrafluoroethylene (PTFE) powder, titanium oxide powder, clay, talc, and barium sulfate.
The fillers are required to be stable for various plasmas such as oxygen as a representative, which are used at process of forming thin film by CVD, fluorine plasma which is used for cleaning the inside of a chamber of a CVD device, and cleaning plasma by fluorine radical of high concentration utilizing NF3 remote plasma.
As fillers stable for these treatment, it is known that an alumina filler and an imide filler are used (for example, see the pamphlet of International Patent Publication No. 00/64980 and the pamphlet of International Patent Publication No. 01/32782). These fillers are stable for treatment of both of oxygen plasma and fluorine plasma, and weight reduction caused by decomposition can be suppressed. Further, it is known that the weight reduction of a filler caused by such treatment affects adversely a semiconductor and a liquid crystal as unnecessary foreign objects (particles) in any form, but the generation of such particles can be suppressed by suppressing the weight reduction. However, it is required to further improve plasma resistance in the production field of semiconductors for which extreme precision process is required.
On the other hand, it has been known that a pigment composition is mixed with a polymer organic material (for example, Japanese Unexamined Patent Publication No. 6-166827). However, the polymer organic material used in the publication assumes materials such as a polyvinyl chloride and a polyolefin which do not contain a fluorine atom. Further, since the pigment composition is used for coloring the polymer organic material, the addition amount is extremely trace and the plasma resistance is not taken into account at all.
Further, antioxidants such as polysaccharides grafted with an antioxidant which has high resistance against decomposition by hydroxy radicals are known (for example, Japanese Unexamined Patent Publication No. 9-12603). However, the antioxidant is usually added for preventing the oxidation of a resin, and there has been no concept that an antioxidant is added to a fluorine containing elastomer having high oxidation resistance, in order to aim the effect of preventing oxidation.
It is an object of the present invention to provide a fluorine containing elastomer composition which maintains heat resistance and processability under directly exposing environment by plasma in the same manner as the inside of a dry-etching device, has little weight change for both of fluorine plasma and oxygen plasma exposing at the production step of a semiconductor, and does not generate foreign objects (particles) at these treatment steps; and a molded article comprising the composition.